Two new species of Asteraceae from Northern and Western Cape, South Africa and a new synonym

Abstract

We recognize two new species of Asteraceae from the winter rainfall belt of South Africa and reduce a third to synonomy. Senecio speciosissimus sp. nov. has been confused with S. coleophyllus Turcz. in the past but is distinguished by its taller stature, larger and more finely serrated leaves, and congested synflorescences containing (6-)15-40 flowerheads. The two species are also geographically separated: S. speciosissimus occurs in the Hottentots Holland and Franschhoek Mountains of the southwestern Cape, whereas S. coleophyllus is endemic to the Riviersonderend Mountains. Chrysocoma hantamensis sp. nov. is a distinctive new species endemic to the Bokkeveld and Roggeveld Plateaus. It is distinguished by its resprouting habit, 3-5-fid leaves and large capitula, 12-15 mm in diameter, with lanceolate, 3-veined involucral bracts, the largest 9-10 x 2 mm. Investigation of the variation in leaf morphology of the two radiate species of Oncosiphon, O. africanum (P.J.Bergius) Källersjö and O. glabratum (Thunb.) Källersjö, reveals that only one species can be maintained, and O. glabratum is accordingly reduced to synonomy in O. africanum.